Within the field of metal can manufacturing, requirements exist to shape the bottom portions of cans. Due to the nature of drawn cans and their contents, the bottom must be formed accurately to provide the required strength. Processes for manufacturing drawn cans include draw and iron machines which generally include a ram-like member for moving a metal can blank into contact with a bottom former machine. Normally, a tool set shapes the desired can bottom shape. The tool set is installed into the bottom former machine. In operation, the draw and iron machine ram pushes the ram-mounted metal can blank against the tool set to form the can bottom. The bottom former machine provides tension to the tool set to hold the tool set in proper position, to form the bottom when impacted with the can material, to cushion the impact of the metal against the tool set, and to return the tool set to its initial position when the drawn and iron press ram withdraws.
As manufacturing processes for making drawn cans have evolved, output demands have steadily grown. At present, can makers searching for equipment that can withstand high production rates of cans per minute are frequently not satisfied with the capabilities of bottom former machines. A principle problem resides in manufacturing a bottom former which is capable of withstanding high can throughput without breakdown or damage.
What has been needed, therefore, has been an improved bottom former for use in shaping a metal can at can cycle rates of greater than 250 cans per minute. What has been further needed has been an improved bottom former for shaping metal cans at a can cycle rate of approximately 300 cans per minute or greater.
What has been further needed has been an improved bottom former to provide excellent tool set tensioning and long life during high cycle rate bottom forming operations.
What has been further needed has been an improved bottom former which employs a double-action principle for tensioning bottom forming doming action with a first tensioning means and for tensioning bottom forming ring action with a second tensioning means during high throughput bottom forming operations.
What has been even further needed has been an improved bottom former employing a double action tensioning system for tensioning the force of metal can blanks contacting associated portions of the bottom former and which provides tensioning for the ring action using automotive style piston means.
What has been even further needed has been a bottom former using a double action tensioning system which includes an automotive style piston for tensioning ring action and which uses a cylinder body in cooperation with resilient spring means for tensioning the doming action of a metal can blank contacting tool set means placed in the bottom former to provide high throughput bottom forming operations.
Other objects and advantages of the invention will appear from the following detailed description which, in connection with the accompanying drawings, discloses embodiments of the invention for purposes of illustration only and not for determination of the limits of the invention.